This invention relates in general to video display support structures and is particularly directed to manually adjustable means for supporting a video display over a wide range of orientations to accommodate various viewing angles.
With the increased use of video displays such as cathode ray tubes (CRT's) in such applications as computer terminals, word processors, communications systems, and video monitoring equipment, increasing emphasis is being placed upon the interface between the user, or viewer, and the video display. Such parameters as video display sweep rates, background color and contrast, and the general viewability of the information on the video display faceplate all affect the quality of video information provided to the viewer and the ability of a system operator to use the thus displayed information.
Increasing at a rate similar to the expanding use of video displays are the fields of environmental and human factors engineering. Within the last several decades designers have approached their tasks with a consideration of the integration of a machine with man's total abilities. Prior to this, the design and structure of machines were made without consideration of man, his limitations, and his safety. The goal is, of course, to maximize productivity while insuring the worker's comfort, safety and well-being. In Europe, the new and rapidly developing field of human factors engineering is generally called ergonomics which is defining strict man-machine interface requirements in ever expanding work environments. The progressive activities in Europe in this field are gaining general acceptance there and will gradually be adopted throughout the industrialized world.
These efforts have addressed the video display environment with particular emphasis on improving the presentation of video information with minimum user inconvenience and hardship. A prime consideration has been directed toward the reduction of glare on the faceplate of the video display. This has been approached primarily with respect to he design and use of various video display tilt mechanisms for minimizing glare.
One approach has been to utilize a friction pivot in the base of the video display whereby the display may be tilted as desired and maintained in position by the friction pivot. One example of this approach can be found in U.S. Pat. No. 3,789,140 to McQueen et al wherein is disclosed an arrangement for manually tilting the primary image screen of a CRT about a horizontal first axis disposed slightly behind the screen by means of a hand wheel exposed through a cabinet enclosing the CRT. Manual torque is applied about a second axis parallel to and behind the first axis. A pinion rockable about the second axis by means of the hand wheel is enmeshed with a concave gear rack concentric with the first axis and has a radius of curvature larger than the pinion for torque transfer. Another approach to a friction pivot-type of CRT tilt arrangement is disclosed in U.S. Pat. No. 4,372,515 to Noonan which discloses a rocking tilt apparatus mounted to the base of a display unit which includes fore/aft retention by a spur gear on an upper support unit and a rack gear on a lower support unit which act to co-locate the origin of the arc of the rocker, the center of gravity and the origin of the arc of the pitch diameter of the spur gear of the display unit through the tilt range. Vertical retention is provided by means of a snubbing device including a spring-loaded friction mechanism which provides infinite actuation throughout the tilt range.
Other, less common, approaches have been used to selectively adjust the tilt angle of a video display. Another such arrangement utilizes a rotatable friction cam positioned beneath an aft portion of the video display for the selective vertical displacement thereof in providing the desired tilt angle. Yet another approach makes use of the combination of a convex lower portion of a display platform and a concave portion of a support stand. The convex portion is inserted in the concave portion in a complementary manner and retained there by means of a spring-loaded wing nut positioned within a longitudinal slot in a friction plate. By displacing the wing nut-spring combination along the longitudinal slot, the convex and concave surfaces are displaced relative to one another and the platform upon which the video display is positioned is tilted as desired. Other approaches involve various complicated arrangements of bellows, flexible members, and various coupled combinations of support links.
To date, an arrangement for the selective positioning of a video display unit which provides for a continuum of self-locking tilt positions over a wide angular range accomplished by means of a single, easily accessible and rapid adjustment which provides precise control of the display's tilt angle is not available. The present invention is intended to supplement the prior art by providing a system which possesses the aforementioned operating characteristics while being low in cost, comprised of easily manufactured parts, and easily assembled and maintained.